One very common problem with electronic musical instruments, such as electrical guitars and basses, is caused by the input jack that connects the instrument to various external electrical devices such as external amplifiers, speakers, and recording devices. These input jacks (often quarter inch diameter female through-hole audio jacks) are typically mounted inside the instrument in a difficult to access area. Usually only a small threaded portion of the jack bushing protrudes outside of the guitar. The jack is usually secured almost flush to the surface of the guitar by a nut and washer. An example of such input jacks is the Switchcraft quarter inch guitar input jack/amp speaker output jack.
Such guitars and jacks are connected and disconnected from external electrical devices at a high frequency, often many times a day, by way of a male plug that connects to the female jack. This connection and disconnection, along with movement of the instrument itself, ends up applying intermittent torque to the input jack. As a result, with repeated use, the jack nut starts to loosen.
Unfortunately, due to the fact that the jack and nut are usually mounted almost flush to the guitar surface, it is difficult or impossible to fix the problem by applying torque to the nut because this torque simply transfers through to the input jack, causing further unwanted jack rotation.
The net effect is that over time and use, the guitar input jack continues to twist and turn inside the guitar during each insertion and removal cycle, and this twisting can cause electrical wires connected to the internal contacts of the jack to fail. At first this failure manifests itself through unwanted noise or signal drop outs caused by the loose wires, and eventually the instrument will fail outright.
At present, methods for fixing input jacks are rather time consuming, and cumbersome. An example of a typical repair procedure consists of a series of steps such as 1) unscrewing the nut and letting the jack fall inside the guitar, 2) using a stiff wire to probe inside the guitar and attempt to hook the loose jack and pull it through the jack opening, 3) inspecting the wires and re-soldering bad connections as need be, 4) attempting to reinsert the unattached jack back into proper position using the stiff wire, 5) attempting to reinsert and tighten the nut, without twisting the jack while doing so.
Thus more satisfactory methods to address the problem of unwanted guitar jack nut loosening, jack movement, and internal wire failure are desirable.